Fitness and lifespan: Is too much exercise harmful?

A new study finds that exercise, even at extreme levels, prolongs life for seniors.

Exercise is widely considered to benefit health, but is there such a thing as too much exercise? Some recent studies suggest so.

For instance, 90 minutes of exercise every day improves mental health, but anything over this threshold is actually worse for mental health than no exercise at all, a recent paper found.

Other research has suggested that there might be cardiovascular disadvantages to excessive amounts of physical exercise.

One study found higher calcification in the arteries of athletes and men who routinely engaged in sports.

So, researchers from the Cleveland Clinic in Ohio set out to investigate whether large amounts of exercise have any bearing on how long a person will live.

To this end, a team led by Dr. Wael Jaber — a cardiologist at the Cleveland Clinic — analyzed the link between aerobic fitness and lifespan in 122,007 people.

“We were particularly interested in the relationship between extremely high fitness and mortality,” explains first study author Dr. Kyle Mandsager, an electrophysiology fellow from the Cleveland Clinic.

“This relationship has never been looked at using objectively measured fitness, and on such a large scale.”

The scientists published their results in the Journal of the American Medical Association Network Open.

Even extreme levels of exercise prolong life

Dr. Jaber and his team retrospectively studied the data from a cohort study of 122,007 people who participated in exercise treadmill testing between January 1, 1991, and December 31, 2014.

The researchers divided the people “by age- and sex-matched cardiorespiratory fitness” into five performance groups: low performance, below average, above average, high, and elite. They determined the aerobic fitness of the participants by administering a stress test.

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The fitness levels of people in the elite group were comparable with those of professional athletes, and they were situated at the 97.7th percentile and above.

Their lifespans were adjusted according to their age, sex, and body mass index (BMI), as well as according to the medication they were taking or other conditions that they had.

Also, “Extremely high aerobic fitness was associated with the greatest survival and was associated with benefit in older patients and those with hypertension,” write the researchers.

People ages 70 and above benefited the most from being in the elite group of cardiorespiratory fitness.

By contrast, poor aerobic fitness was just as strong a predictor of early death as smoking, heart disease, or diabetes.

“Cardiorespiratory fitness,” conclude the authors, “is a modifiable indicator of long-term mortality, and healthcare professionals should encourage patients to achieve and maintain high levels of fitness.”

“Aerobic fitness is something that most patients can control. And we found in our study there is no limit to how much exercise is too much […] Everyone should be encouraged to achieve and maintain high fitness levels.”